1. Field of the Invention
The present invention relates to an apparatus and method for extracting query objects from a video sequence and generating object-label images for the query objects.
2. Description of the Related Art
In conventional technology, query objects are manually extracted from each frame of a moving picture sequence in order to generate object-labeled images in the moving picture. Methods for automatically extracting objects without need for additional operation have been recently announced.
Methods of extracting objects from images include motion based extraction methods and feature based extraction methods. Motion based extraction methods include frame difference based extraction methods, background subtraction based extraction methods, and motion analysis based extraction methods. Frame difference based extraction methods, as disclosed in U.S. Pat. Nos. 5,500,904 and 5,109,435, extract motion by calculating a difference in brightness between continuous frames of an image. In background subtraction methods, as disclosed in U.S. Pat. No. 5,748,775, a background image is recovered by the temporal change of an image feature parameter and an object region is extracted by the difference between an original image and the background image. In motion analysis methods, as disclosed in U.S. Pat. No. 5,862,508, a motion region is extracted by calculating the direction of movement and the speed of a moving object.
However, such object region extraction methods can only be used when the speed of movement of an object is appropriate. It is difficult to apply such methods to a still image, a slow moving object, or a fast moving object.
An approach of using a feature value of an object region includes a template matching method as disclosed in U.S. Pat. No. 5,943,442, a multi-value threshold method as disclosed in U.S. Pat. No. 5,138,671, and a feature value matching method. In order to use these methods in extracting a query object from moving picture data, the methods must be applied to all frames based on query objects. Therefore, a considerable amount of time is required.